1. Field of the Invention
The present in invention relates to an IC socket used for the testing of various IC packages, such as QFP (Quad Flat Package), SOP (Small Outline Package) and so forth.
Typically, IC packages are tested in some manner to ensure their proper functions. The present invention relates to the IC socket which enable various tests for a plurality of IC packages quickly and certainly.
2. Description of Prior Art
One of the tests for IC packages is the burn-in test, in which the IC package is inserted into the IC socket and thereafter installed within a convection oven for testing high-temperature characteristics of the IC package under an elevated temperature.
As to the IC socket to be used for the above-mentioned bur-in test, there are some applications in which the IC sockets adapted to testing by automatic process are disclosed. For example, U.S. Pat. Nos. 4,623,208 and 4,886,470 disclose IC sockets adapted to automated-type testing apparatus.
FIGS. 7 to 9 show the conventional IC socket disclosed in U.S. Pat. No. 4,623,208. In further detail, FIG. 7 is a perspective view showing normal condition before testing, FIG. 8 is an exploded perspective view showing overall construction, FIG. 9 is a section of the condition, in which the IC package is inserted, taken along line B--B of FIG. 7, and FIG. 10 is a section of the condition, in which the IC package is installed, taken along line B--B of FIG. 7.
FIGS. 11 to 13 show the conventional IC socket disclosed in U.S. Pat. No. 4,886,470. In further detail, FIG. 11 is a perspective view in the normal state before testing, FIG. 12 is a section of the condition, in which a lead of the IC package is contacting the contact, taken along line C--C of FIG. 11, and FIG. 13 is a section of the condition, in which a lead of the IC package is held in non-contact with the contact, taken along line C--C of FIG. 11.
As illustrated, the above-mentioned two kinds of IC sockets comprise socket bodies 10, covers 20 and a plurality of contacts 30. Each of the contacts 30 has a contact section 40 for electrical contact with the lead L of the IC package P (strictly speaking, a pad of a chip carrier corresponds to the lead in the first prior art example FIGS. 7 to 10), a cantilever section 50 for rotating the contact section, 40 to enable connection and releasing between the lead L and each contact 30.
Here, when the cover 20 is depressed downwardly against a resilient force (reacting force) of the contact 30, the above-mentioned contact 30 is forcingly displaced outwardly to place the contact 30 and the lead L of the IC package P into the non-contacting state to release connection therebetween. Accordingly, in this condition, insertion and removal (loading and unloading) of the IC package P can be performed. When depression force on the cover 20 is removed, the contact 30 is rotated in the reverse direction to restore connection with the lead L of the IC package P.
However, the above-mentioned IC socket does not have an operation stand-by mechanism. Therefore, particularly when the test for the IC package is performed by manual operation, loading and unloading od the IC package has to be done by downwardly depressing the cover 20 against the reacting force of the contacts, making the operation very difficult. In order to solve this problem, an IC socket provided with an operation stand-by mechanism of the cover has been disclosed in Unexamined Patent Publication (Kokai) No. 64-65782, for example.
FIGS. 14 to 17 are illustrations showing the prior art in Unexamined Patent Publication No. 64-65782. In further detail, FIG. 14 is a perspective view showing overall construction of the IC socket, FIG. 15 is a perspective view of the IC socket in a condition where the IC socket and the contact are held in a non-contacting state, FIG. 16 is a partial side section of the IC socket in the foregoing condition, and FIG. 17 is a partial side section of the IC socket in a condition where the IC package and the contact are held in a contacting state. It should be noted that the similar construction elements to the foregoing will be represented by the same reference numerals.
As shown, this IC socket enable the establishment of the operation stand-by state by hooking latch 70, formed integrally with the socket body 10, to projections 80 of the cover. With the above-mentioned IC socket, the cover can be held at the lowermost position. Namely, since the contact 30 can be held in the contact releasing position, it is unnecessary to forcingly depress the cover with an external force for facilitating loading and unloading of the IC package.